Vaccine-Induced Subacute Thyroiditis (De Quervain’s) after mRNA Vaccine against SARS-CoV-2: A Case Report and Systematic Review

COVID-19 vaccination and thyroiditis

At the end of 2019, the world began to fight the coronavirus disease 2019 (COVID-19) pandemic caused by the severe acute respiratory syndrome coronavirus-2. Many vaccines have quickly been developed to control the epidemic, and with the widespread use of vaccines globally, several vaccine-related adverse events have been reported. This review mainly focused on COVID-19 vaccination-associated thyroiditis and summarized the current evidence regarding vaccine-induced subacute thyroiditis, silent thyroiditis, Graves' disease, and Graves' orbitopathy. The main clinical characteristics of each specific disease were outlined, and possible pathophysiological mechanisms were discussed. Finally, areas lacking evidence were specified, and a research agenda was proposed.

Insights into SARS-CoV-2-associated subacute thyroiditis: from infection to vaccine

Since the COVID-19 emergence as a global pandemic in March 2020, more than 5 million SARS-CoV-2-related deaths have been globally documented. As the pandemic progressed, it became clear that, although the infection is mainly characterized as a respiratory disease, it also affects other organs and systems, including the thyroid gland. Indeed, emerging evidence suggests that SARS-CoV-2 can act as a trigger for various thyroid disorders, for example, subacute thyroiditis (SAT), Grave's disease, and non-thyroidal illness syndrome. The entry of SARS-CoV-2 into the host cells is mainly mediated by the ACE2-receptor, making organs and systems with high expression of this receptor, such as the thyroid gland, highly vulnerable to COVID-19. Accumulating data propose that SAT may be an underestimated manifestation of COVID-19 infection. Importantly, if SAT remains unrecognized, it may trigger or aggravate potential other complications of the disease, for example, respiratory insufficiency and cardiovascular complications, and thus negatively influence prognosis. Moreover, recent case reports, case series, and systematic reviews highlight SAT as a potential side effect of the vaccination against SARS-CoV-2. The present review aims to raise awareness of SARS-CoV-2-associated- and post-vaccination subacute thyroiditis, to discuss recent evidence regarding its pathophysiology, and to present useful information for this special form of SAT related to daily clinical practice.

A Literature Review on SARS-CoV-2 and Other Viruses in Thyroid Disorders: Environmental Triggers or No-Guilty Bystanders?

A growing number of findings indicate a relationship between COVID-19 infection and thyroid dysfunction. This association is also strengthened by knowledge on the potential of viral infections to trigger thyroid disorders, although the exact underlying pathogenetic process remains to be elucidated. This review aimed to describe the available data regarding the possible role of infectious agents, and in particular of SARS-CoV-2, in the development of thyroid disorders, summarizing the proposed mechanisms and levels of evidence (epidemiological, serological or direct presence of the viruses in the thyroid gland) by which the infection could be responsible for thyroid abnormalities/diseases. Novel data on the association and mechanisms involved between SARS-CoV-2 vaccines and thyroid diseases are also discussed. While demonstrating a clear causal link is challenging, numerous clues at molecular and cellular levels and the large amount of epidemiological data suggest the existence of this relationship. Further studies should be taken to further investigate the true nature and strength of this association, to help in planning future preventive and therapeutic strategies for more personal and targeted care with attention to the underlying causes of thyroid dysfunction.

A Novel Finding of an HLA Allele's and a Haplotype's Relationship with SARS-CoV-2 Vaccine-Associated Subacute Thyroiditis

Subacute thyroiditis (SAT) is a thyroid disease associated with viral infections. Its relationship with major histocompatibility complex (MHC) antigens was shown before. SAT cases triggered by different types of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines have been reported. In this study, human leukocyte antigen (HLA) genotypes of 27 SAT patients (13 vaccine-associated (V-SAT) and 14 non-SARS-CoV-2-infection non-vaccine-associated (non-V-SAT)) were compared with those of 362 healthy donors. HLA analyses were performed with low-resolution DNA-based sequence-specific oligonucleotide or sequence-specific primer methods. Statistical analyses were performed using IBM SPSS Statistics 25 and Stata/MP 14.1 with the hapipf function. Allele and haplotype frequencies were estimated by PyPop and gene[RATE] tool programs. The allele frequencies of HLA-A*11, HLA-B*35, and HLA-C*04 were higher in the patient groups. Both the allele frequency of HLA-A*11 and the haplotype frequency of A*11-B*35-C*04 were higher in the V-SAT group. The A*11-B*35-C*04 haplotype, including all three loci of MHC class I genes, is shown to be associated with the disease for the first time, especially in the V-SAT group. This finding will contribute to a better understanding of the etiopathogenesis of vaccine-associated SAT and the role of HLA genotypes in the functioning mechanisms of the SARS-CoV-2 vaccines.

Subacute (De Quervain's) thyroiditis presenting as painful thyroid nodule suspicious of papillary thyroid carcinoma: Case report

INTRODUCTION

We report a case of subacute thyroiditis (SAT) in a 29 -year-old female who presented with painful thyroid swelling.

PRESENTATION OF CASE

Patient presented with neck pain, tender neck swelling and generalized fatigue. She had no history of neck or chest radiation or compressive symptoms. Ultrasound (US) imaging reveled bilateral nodules of the thyroid gland. Lymph nodes were unremarkable. FNAC was suspicious for papillary thyroid carcinoma. The patient was discussed at the thyroid multidisciplinary meeting, and after deliberation the decision was to offer the patient the choice of repeating FNAC of the bilateral nodules in one month or to proceed with total thyroidectomy.

DISCUSSION

Despite being aware of the possibility that the final pathology could be benign, the patient insisted on total thyroidectomy, given that her FNAC results were suspicious of papillary thyroid carcinoma, and in order to avoid recurrence of the condition and the pain. Following the patient's preference, total thyroidectomy was performed, and surgery was not straightforward as intraoperatively, there was a diffusely inflamed gland. Histopathology findings revealed benign pathology. Follow up until 1.5 years showed that the patient was satisfied, and with normal voice.

CONCLUSION

SAT is a painful but potentially self-limiting. In some cases, FNAC findings might be suspicious for papillary thyroid carcinoma. Treatment is mostly conservative, but if the pain is severe and the patient insists on surgery as in our case despite the possibility of the condition being of benign pathology, then surgery should be undertaken.

The New Entity of Subacute Thyroiditis amid the COVID-19 Pandemic: From Infection to Vaccine

This is a review of full-length articles strictly concerning subacute thyroiditis (SAT) in relation to the SARS-CoV-2 virus infection (SVI) and COVID-19 vaccine (COV) that were published between the 1st of March 2020 and the 21st of March 2022 in PubMed-indexed journals. A total of 161 cases were reported as follows: 81 cases of SAT–SVI (2 retrospective studies, 5 case series, and 29 case reports), 80 respective cases of SAT–COV (1 longitudinal study, 14 case series, 17 case reports; also, 1 prospective study included 12 patients, with 6 patients in each category). To our knowledge, this represents the largest cohort of reported cases until the present time. SAT–SVI was detected in adults aged between 18 and 85 years, mostly in middle-aged females. SAT–COVID-19 timing classifies SAT as viral (synchronous with infection, which is an original feature of SATs that usually follow a viral infection) and post-viral (during the recovery period or after infection, usually within 6 to 8 weeks, up to a maximum 24 weeks). The clinical spectrum has two patterns: either that accompanying a severe COVID-19 infection with multi-organ spreading (most frequent with lung involvement) or as an asymptomatic infection, with SAT being the single manifestation or the first presentation. Either way, SAT may remain unrecognized. Some data suggest that more intense neck pain, more frequent fever, and more frequent hypothyroidism at 3 months are identified when compared with non-SAT–SVI, but other authors have identified similar presentations and outcomes. Post-COVID-19 fatigue may be due to residual post-SAT hypothyroidism. The practical importance of SAT–SVI derives from the fact that thyroid hormone anomalies aggravate the general status of severe infections (particular concerns being tachycardia/arrhythmias, cardiac insufficiency, and ischemic events). If misdiagnosed, SAT results in unnecessary treatment with anti-thyroid drugs or even antibiotics for fever of unknown cause. Once recognized, SAT does not seem to require a particular approach when compared with non-COVID-19 cases, including the need for glucocorticoid therapy and the rate of permanent hypothyroidism. A complete resolution of thyroid hormone anomalies and inflammation is expected, except for cases with persistent hypothyroidism. SAT–COV follows within a few hours to a few weeks, with an average of 2 weeks (no particular pattern is related to the first or second vaccine dose). Pathogenesis includes molecular mimicry and immunoinflammatory anomalies, and some have suggested that this is part of ASIA syndrome (autoimmune/inflammatory syndrome induced by adjuvants). An alternative hypothesis to vaccine-related increased autoimmunity is vaccine-induced hyperviscosity; however, this is supported by incomplete evidence. From what we know so far concerning the risk factors, a prior episode of non-SVI–SAT is not associated with a higher risk of SAT–COV, nor is a previous history of coronavirus infection by itself. Post-vaccine SAT usually has a less severe presentation and a good outcome. Generally, the female sex is prone to developing any type of SAT. HLA susceptibility is probably related to both new types of SATs. The current low level of statistical evidence is expected to change in the future. Practitioners should be aware of SAT–COV, which does not restrict immunization protocols in any case.